A series of nine interrelated studies has been designed to examine the influences of alcohol upon control-use and driving performance as well as the interactions of alcohol and fatigue, noise, task complexity, track configuration, instructional set, and extraversion. The principal apparatus would be a standard domestic station wagon equipped to record the following measures in analog form: steering position, accelerator position, brake pressure, car position, and a lateral and longitudinal acceleration. Most driving would be done on a one-mile section of a relatively straight, private road isolated from traffic. In order to maximize the measurable influences of alcohol, the divided attention aspect of driving would be emphasized, e.g., the concurrent monitoring of driving speed and lateral position would be required to various degrees in most experiments. A repeated-measurement factorial design will be used in each study, with each subject being tested on at least four days. The first day will be devoted to practice in order to reduce learning and transfer effects. On the remaining 3 days, the subject will be tested following consumption of three different alcohol dosages (target blood alcohol concentrations: O, 50, 100 mg percent) with only a single dosage being given each day. Control subjects receiving placebo beverages would be used to determine the nature and extent of learning and transfer effects. The expected results should aid in a more precise specification of: (a) the conditions under which performance is susceptible to alcohol effects, (b) the nature of effects with respect to the manner in which control-use behavior is changed, (c) the meaning of control-use patterns in terms of the state of the driver, and (d) the relation of these patterns to specific driving performance. Such information should be of use in reducing alcohol-associated crashes through education concerning the complex and insidious influences of alcohol upon performance and through its application to the design of the driving environment as well as to the design of hardware and procedures for detecting impaired drivers.